HAP-40 Bunka Black Kebony Octagon 190mm (7.5″)

HAP-40 Bunka Black 190mm (7.5″) is a multi-purpose knife from our HAP-40 series which we designed in collaboration with the Yoshida Hamono smithy. With this series, we fused Japanese tradition and knowledge of blade design and materials processing, and what came out is a versatile kitchen knife made of powder steel that is simple to use and maintain.

HAP-40 Bunka Black embodies the best characteristics we could possibly expect from a kitchen knife: Versatile use: meat, fish and vegetables. Wide blade at the handle allows for comfortable (and lengthy) work with either right or left hand. The gentle belly is suited to either long or short cuts. The heel of the blade is straight and intended for chopping. The blade tapers off towards the tip and lends itself perfectly to precise work with food. Fine – and extremely long-lasting – sharpness. Very hard powder steel with a hardness of 68 HRC.  Simple maintenance and sharpening.

BLADE SHAPE:
With its typical functionality, Bunka design is intended for versatile use in Western cuisine. It has a flexible profile that is wide enough at the handle, a gently designed belly of the blade suitable for making either long or short cuts, a flat back side of the blade, and a thin tip for precise work with food.

HANDLE:
This knife features a traditional Japanese wooden handle (Wa) made of Kebony wood with buffalo horn ferrule. A universal, octagonal shape comfortably fits in the hands of both right- and left-hand users.

STEEL:
The secret of this knife lies in extremely (68 HRC!) hard core made of a somewhat exotic and currently one of the most mysterious and attractive steels produced in Japan (at least as far as kitchen knives are concerned): Hitachi’s HAP-40 steel that fits into the category of modern and technologically advanced steels. HAP-40 is fine-grained enough to sharpen very well, and knives from this steel keep their sharpness 3-5 times longer than traditional knives. An interesting fact is that, considering it is a powder steel, it has an extremely small content of chromium (around 4%) and can react as a high-carbon steel in specific circumstances.

This steel is heat-treated to an incredible 68 HRC, yet it can still be relatively easily sharpened on whetstones. It is extremely tough, and so not as likely to chip along the edge as the steel used in traditional knives.

COMPOSITION: 1.27–1.37% carbon (C), 3.70–4.70% chromium (Cr), 5.60–6.40% tungsten (W), 4.60–5.40% molybdenum (Mo), 2.80–3.30% vanadium (V) and 7.50–8.50% cobalt (Co).

LAMINATION:
Osamu-san chose a warikomi (also called “split and insert”) method. A glowing hot piece of iron is split and a piece of steel is inserted. The new material is now forged into one piece composed of a very hard steel core in a jacket of two external layers of softer, stainless steel. This creates a highly durable kitchen knife with a slightly more pliable core. The main advantage of these knives is that they are thin, sharp and retain their edge very well.

GEOMETRY:
It has a double bevel (symmetrical) blade.

BLADE FINISH:
The blade has a dark finish which is the reason why this look is also called kuro-uchi – the word “kuro” means black. This look is traditional and robust, with an unprocessed top part of the blade that has already developed a dark patina.

ABOUT THE BLACKSMITH:
The knife is manufactured at the smithy of Yoshida Hamono in Japan, a family company with an age-long tradition in manufacturing state-of-the-art tools and Japanese swords, i.e., katanas, by hand. Yoshida Hamono has a great deal of experience forging ZDP-189 steel in the traditional manner.